Jimmy hurried off, but by the time he returned, Donovan was sitting up and declaring himself quite all right again. He had to listen to a short lecture from Poirot on the necessity of caution in sniffing at possibly poisonous substances.
‘I think I’ll be off home,’ said Donovan, rising shakily to his feet. ‘That is, if I can’t be any more use here. I feel a bit wonky still.’
‘Assuredly,’ said Poirot. ‘That is the best thing you can do. M. Faulkener, attend me here a little minute. I will return on the instant.’
He accompanied Donovan to the door and beyond. They remained outside on the landing talking for some minutes. When Poirot at last re-entered the flat he found Jimmy standing in the sitting-room gazing round him with puzzled eyes.
‘Well, M. Poirot,’ he said, ‘what next?’
‘There is nothing next. The case is finished.’
‘What?’
‘I know everything—now.’
Jimmy stared at him. ‘That little bottle you found?’
‘Exactly. That little bottle.’
Jimmy shook his head. ‘I can’t make head or tail of it. For some reason or other I can see you are dissatisfied with the evidence against this John Fraser, whoever he may be.’
‘Whoever he may be,’ repeated Poirot softly. ‘If he is anyone at all—well, I shall be surprised.’
‘I don’t understand.’
‘He is a name—that is all—a name carefully marked on a handkerchief!’
‘And the letter?’
‘Did you notice that it was printed? Now, why? I will tell you. Handwriting might be recognized, and a typewritten letter is more easily traced than you would imagine—but if a real John Fraser wrote that letter those two points would not have appealed to him! No, it was written on purpose, and put in the dead woman’s pocket for us to find. There is no such person as John Fraser.’
Jimmy looked at him inquiringly.
‘And so,’ went on Poirot, ‘I went back to the point that first struck me. You heard me say that certain things in a room were always in the same place under given circumstances. I gave three instances. I might have mentioned a fourth—the electric-light switch, my friend.’
Jimmy still stared uncomprehendingly. Poirot went on.
‘Your friend Donovan did not go near the window—it was by resting his hand on this table that he got it covered in blood! But I asked myself at once—why did he rest it there? What was he doing groping about this room in darkness? For remember, my friend, the electric-light switch is always in the same place—by the door. Why, when he came to this room, did he not at once feel for the light and turn it on? That was the natural, the normal thing to do. According to him, he tried to turn on the light in the kitchen, but failed. Yet when I tried the switch it was in perfect working order. Did he, then, not wish the light to go on just then? If it had gone on you would both have seen at once that you were in the wrong flat. There would have been no reason to come into this room.’
‘What are you driving at, M. Poirot? I don’t understand. What do you mean?’
‘I mean—this.’
Poirot held up a Yale door key.
‘The key of this flat?’
‘No, mon ami, the key of the flat above. Mademoiselle Patricia’s key, which M. Donovan Bailey abstracted from her bag some time during the evening.’
‘But why—why?’
‘Parbleu! So that he could do what he wanted to do—gain admission to this flat in a perfectly unsuspicious manner. He made sure that the lift door was unbolted earlier in the evening.’
‘Where did you get the key?’
Poirot’s smile broadened. ‘I found it just now—where I looked for it—in M. Donovan’s pocket. See you, that little bottle I pretended to find was a ruse. M. Donovan is taken in. He does what I knew he would do—unstoppers it and sniffs. And in that little bottle is ethyl chloride, a very powerful instant anaesthetic. It gives me just the moment or two of unconsciousness I need. I take from his pocket the two things that I knew would be there. This key was one of them—the other—’